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Select More > Link to display the Link dialog box.
Ensure that the Jira Issue item is selected at the left of the dialog box and then choose the type of link to be created from the This issue drop-down list

Share a

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issue with a customer  

When a licensed Jira Service Management user opens issue, the link differs from the public link used for the Customer Portal.
If the Licensed user wants to share an issue to a customer,  use the view customer request button, and then copy the link for sharing.

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